// Problem: 
// Contest: 
// URL: 
// Memory Limit: 
// Time Limit: 
// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#include<bits/stdc++.h>
using namespace std;
#define int long long
inline int read(){
	int s=0,w=1;
	char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')w=-1;ch=getchar();}
	while(ch>='0'&&ch<='9') s=s*10+ch-'0',ch=getchar();
	return s*w;
}
int n,ans=0;
vector<int> v,w;
void merge(int l,int r)
{
	if(l==r)return ;
	int mid=l+r>>1;
	merge(l,mid);
	merge(mid+1,r);
	for(int i=l,j=l,k=mid+1;i<=r;i++)
	{
		if(j==mid+1||(v[j]>v[k]&&k<r+1))w[i]=v[k++];
		else 
		{
			w[i]=v[j++];
			ans+=k-mid-1;
		}
	}
	for(int i=l;i<=r;i++)v[i]=w[i];
}
signed main()
{
	int t=1;
//	cin>>t;
	while(t--)
	{
		cin>>n;
		w=v=vector<int> (n+1);
		for(int i=1;i<=n;i++)
		{
			scanf("%lld",&v[i]);
		}
		merge(1,n);
		printf("%lld",ans);
	}
	return 0;
}
